1. Field of the Invention
The present invention relates generally to plumbers' tools of the type employing a helically wound coiled spring or "snake" which is rotated and inserted into waste lines to remove blockages. More particularly the invention concerns an improved device for pressurally gripping the coiled spring to cause its rotation as the casing containing the spring is rotated by an electric motor.
2. Discussion of the Prior Art
One of the most successful motor driven, lever operated, prior art portable plumbing tools ever developed is the tool described in U.S. Pat. No. 3,449,782. The present invention is an improvement upon this device.
The tool of the present invention is characterized by having a hand held motor at one end of a coiled spring, a storage housing and a manually operated chuck means at the other end through which the spring passes. Several variations of devices of this general type have been suggested. However, most are difficult to operate principally because of a faulty design of the actuating means by which the chuck is moved into and out of gripping engagement with the spring. Unless this actuating means is properly designed the operator cannot satisfactorily regulate the pressure being applied to the spring to controllably cause its rotation as the storage housing is rotated. If too much pressure is applied to the spring the motor will become overloaded and the tool will fail to function properly creating a possibly dangerous situation. If too little pressure is applied to the spring slippage will result and the spring will not rotate.
While the device of the previously mentioned U.S. Pat. No. 3,449,782 was far superior to any devices in competition therewith, the design of the actuating means thereof did not provide for effortless and smooth actuation of the chuck assembly. In a highly novel manner presently to be described, the tool of the present invention overcomes the drawbacks of the prior art predecessor devices by providing a unique double fulcrum arrangement which permits a substantial increase in the controllability of the gripping power of the chucking arrangement of the tool.